#define _CRT_SECURE_NO_WARNINGS
int sum(int n)
{
	if (n % 2 == 0)
		return n;
	else
		return n * 2;
}
#include <stdio.h>
int main()
{
	int n;
	scanf("%d", &n);
	printf("%d",sum(n));
	return 0;
}